lib/libm/src/k_cosf.c

   1 /* k_cosf.c -- float version of k_cos.c
   2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   3  */
   4
   5 /*
   6  * ====================================================
   7  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   8  *
   9  * Developed at SunPro, a Sun Microsystems, Inc. business.
  10  * Permission to use, copy, modify, and distribute this
  11  * software is freely granted, provided that this notice
  12  * is preserved.
  13  * ====================================================
  14  *
  15  * $NetBSD: k_cosf.c,v 1.7 2002/05/26 22:01:53 wiz Exp $
  16  * $DragonFly: src/lib/libm/src/k_cosf.c,v 1.1 2005/07/26 21:15:20 joerg Exp $
  17  */
  18
  19 #include <math.h>
  20 #include "math_private.h"
  21
  22 static const float
  23 one =  1.0000000000e+00, /* 0x3f800000 */
  24 C1  =  4.1666667908e-02, /* 0x3d2aaaab */
  25 C2  = -1.3888889225e-03, /* 0xbab60b61 */
  26 C3  =  2.4801587642e-05, /* 0x37d00d01 */
  27 C4  = -2.7557314297e-07, /* 0xb493f27c */
  28 C5  =  2.0875723372e-09, /* 0x310f74f6 */
  29 C6  = -1.1359647598e-11; /* 0xad47d74e */
  30
  31 float
  32 __kernel_cosf(float x, float y)
  33 {
  34         float a,hz,z,r,qx;
  35         int32_t ix;
  36         GET_FLOAT_WORD(ix,x);
  37         ix &= 0x7fffffff;                       /* ix = |x|'s high word*/
  38         if(ix<0x32000000) {                     /* if x < 2**27 */
  39             if(((int)x)==0) return one;         /* generate inexact */
  40         }
  41         z  = x*x;
  42         r  = z*(C1+z*(C2+z*(C3+z*(C4+z*(C5+z*C6)))));
  43         if(ix < 0x3e99999a)                     /* if |x| < 0.3 */
  44             return one - ((float)0.5*z - (z*r - x*y));
  45         else {
  46             if(ix > 0x3f480000) {               /* x > 0.78125 */
  47                 qx = (float)0.28125;
  48             } else {
  49                 SET_FLOAT_WORD(qx,ix-0x01000000);       /* x/4 */
  50             }
  51             hz = (float)0.5*z-qx;
  52             a  = one-qx;
  53             return a - (hz - (z*r-x*y));
  54         }
  55 }